Expandable metal-to-metal seal

ABSTRACT

A seal includes a seal body configured to form a teardrop shaped seal member upon axial compression of the seal body; a gauge ring in operable communication with the seal body and capable of applying an axial load on the seal body and method

BACKGROUND

In the hydrocarbon recovery arts, seals are endlessly used to effectworking conditions supportive of desired production fluid recovery. Inrecent years engineering and development dollars have been spentattempting to improve both pressure holding capacity and longevity. Onetype of seal receiving significant interest is a metal-to-metal seal dueto the fact that of many types metal seals exhibit high temperaturetolerance, high-pressure capability, robust chemical resistance, andhigh durability.

Although there are many types of seals that utilize metal as a ceilingstructure, those receiving the most attention contemporaneously with thefiling of this document are heavier wall metal seals that are deformedin order to bring them into contact with another structure in a mannerwhere seal is created against that other structure. While such seals doindeed provide all of the above noted benefits with respect tometal-to-metal seals, recovery sometimes can be difficult. Such sealsexperience a high degree work hardening when they are set and because ofthis work hardening experience loss of resilience. This is of course anissue with respect to stretching a seal out to retrieve it from thewellbore.

SUMMARY

A seal includes a seal body having a bridge; a leg extending from thebridge; and a gauge ring in operable communication with the leg, thegauge ring including a support surface for the leg, the gauge ringinteracting with the seal body to cause axial compression thereof,thereby forming a teardrop configuration of the bridge.

A seal includes a seal body configured to form a teardrop shaped sealmember upon axial compression of the seal body; a gauge ring in operablecommunication with the seal body and capable of applying an axial loadon the seal body.

A downhole sealed system, includes at least one tubular member of thetubular system disposed in one of radially inwardly of or radiallyoutwardly of another component of the system; and a seal disposedannularly at the tubular member, the seal having a teardrop shaped crosssection.

A method for setting a seal in a target tubular includes axiallycompressing a seal; bending the bridge into a teardrop shape in sealingcontact with the tubular; and substantially preventing introduction ofbending stress into the leg.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alikein the several Figures:

FIG. 1 is a schematic view of one embodiment of a seal disclosed hereinin a run in condition;

FIG. 2 is a schematic view of the embodiment of FIG. 1 illustrated in aset position; and

FIGS. 3A-3F represent sequential views of the seal of FIG. 1 withdrawingfrom the set position during retrieval.

DETAILED DESCRIPTION

Initially it is to be understood that the seal created as disclosedherein performs better in one respect due to its teardrop crosssectional shape. The shape itself helps to absorb backlash in thesetting force and therefore renders the seal more reliable. This isdescribed in more detail in connection with one embodiment of a sealthat forms the stated shape. It is also to be understood that althoughthe drawings hereof illustrate a seal that bows radially outwardly, thecomponents can easily be reversed such that the seal will bow radiallyinwardly such that the seal will be formed against a tubular radiallyinwardly disposed of the seal device rather than radially outwardly ofthe seal device as specifically illustrated.

Referring to FIG. 1, an embodiment of a seal 10 in accordance with thisdisclosure is illustrated. The seal 10 comprises a seal body 12 having afirst end ring 14 and a second end ring 16. Seal body 12 comprises aseal bridge 18 and first and second seal legs 20 and 22. The legsterminate at roots 36 and 38. Seal 10 further includes configurationscapable of causing the seal body to collapse axially into a set positionsuch as, for example, two gauge rings 24 and 26, each disposed inoperable communication with one end of the seal body 12. While gaugerings are specifically disclosed, the terms as used herein are intendedto convey any configuration capable of loading the seal body 12 to setthe seal 10 and to be instrumental in retrieving the seal 10. This“operable communication” as noted is, in one embodiment, a fixedconnection to each end ring 14 and 16, respectively, while in otherembodiments it can float. The fixed connection as illustrated isadjacent roots 36 and 38. The gauge rings 24 and 26 are also insupportive communication with the legs 20 and 22, respectively. As canbe readily seen in FIG. 1, each gauge ring includes an angled surfaceidentified by the numerals 28 and 30, respectively. The surfaces 28 and30 are roughly parallel to the legs 20 and 22 although not in contacttherewith prior to the setting sequence for the seal 10. These surfaces28 and 30 come in contact with the legs 20 and 22 during the settingsequence to support the same as will be better appreciated afterexposure to the operation section of this document.

Also visible in FIG. 1 are two radiuses 32 and 34 provided one on eachof gauge rings 24 and 26, respectively. The radiuses, in one embodiment,are in a range of about 0.13 to about 0.16 inch. While a wider range isalso operable, it has been found that the range of about 0.13 to about0.16 is effective in minimizing stress in the seal body 12 duringsetting. This is also the purpose for which the angled surfaces 28 and30 are provided. The angle of the surfaces 28 and 30 is selected tocoincide with the angle of legs 20 and 22 as noted above in order tosupport these structures thereby preventing significant bending thereofduring setting of the seal 10. Angles for surfaces 28 and 30 range inparticular embodiments from about 45 degrees to about 90 degrees. Asillustrated, the angles are both about 60 degrees. The range indicatedhas been found to work well though it is to be appreciated that anglesoutside the exemplary range are also contemplated but may not reducestress in legs 20 and 22 to the extent of the reduction found in theidentified range.

The prevention of bending reduces work hardening effects that wouldotherwise be experienced in these locations. Such reduction in workhardening effectively equates to more residual elasticity in thematerial of the seal in locations of the seal (legs and roots) that willbe subject to bending stresses upon retrieval of the seal. Duringsetting of the seal the bending stress is localized in the bridge 18 andin retrieval, bending stress is localized in the legs and roots.Generally, materials that are somewhat ductile can be bent at least oncewithout breaking, work hardening, of course, building within thematerial during this and any subsequent bending stress. Since in thedisclosed seal, the configuration ensures that bending is experiencedsubstantially only once in each localized area of the seal 12, thelikelihood of each localized area enduring sufficient stress to ruptureis dramatically reduced. The protective action of the surfaces 28 and 30extends to both the legs 20 and 22 and leg roots 36 and 38,respectively. By avoiding stress in these structures during setting ofthe seal 10, the ability to retrieve the seal 10, without suffering arupture of the seal, is facilitated. It is further noted that in theseal 10, nowhere is there a sharp bend of the material of the seal body12. Rather, all bends are gradual thereby spreading the stress over abroader area of the seal material. This avoids point stresses thatgenerally create weaknesses in the seal both while being initiallydeformed and certainly while being retrieved. As such, embodiments ofthe invention alleviate the problem found in the prior art as notedabove.

One last point that should be made prior to a discussion of actuation ofan exemplary seal 10 is that seal body 12 is a machined part in oneembodiment such that there are no, or extremely little, residualstresses in the body 12 in the position shown in FIG. 1. Little residualstress in the seal body 12 prior to deformation in use is a benefit asthis helps to minimize the magnitude of stresses experienced by the body12 during setting. As the purpose of this configuration is the reductionin initial stress of the body 12, it is noted that an alternatearrangement is that body 12 could be a preformed and stress relievedcomponent for some applications or even a molded component for someapplications. Again, the important thing is that the positionillustrated at the roots 36 and 38 is a position of the seal body 12that should exist prior to setting of the seal, with very littleresidual stress. Further, stress is not introduced into roots 36 and 38during the setting of the seal 10 due to the configuration of the gaugerings thereby retaining elasticity of the material of the body 12 in thelegs and the roots. This is to the operator's advantage during retrievalof the seal 10, as noted above.

Referring now to FIGS. 1 and 2 simultaneously, setting of seal 10 isillustrated. Seal 10 is set through the application of an axial loadresulting in the space between the gauge rings diminishing. This can beeffected in a number of ways including: 1) by causing at least one ofthe gauge rings to move toward the other of the gauge rings while the“other” gauge ring is stationary; 2) to cause one ring to move towardthe “other” ring while the other ring moves away from the one ring moreslowly than the one ring is moving toward the other ring; or 3) to causeone ring to move toward the other ring while the other ring is movingtowards the one ring. For illustrative purposes, the drawings anddescription herein are directed to an embodiment where gauge ring 24 ismoved while gauge ring 26 remains stationary through, for example,operable contact with an anchoring mechanism (not shown).

Due to the shape of body 12, one will appreciate that axial shorteningthereof will necessarily cause the body 12 to bulge outwardly. What maynot be immediately appreciated from the drawings, however, is the actionof gauge rings 24 and 26 on the process. As gauge rings 24 and 26 aremoved so that they are closer to one another, surfaces 28 and 30 comeinto contact with legs 20 and 22, respectively. As contact is made inthis location, the legs 20 and 22 are substantially supported such thatthey and the roots 36 and 38 from which the legs extend experience verylittle bending stress while the seal 10 is being set. Since the distancebetween gauge rings 24 and 26 is still being reduced, however, the sealbody 12 must necessarily still react. Due to the supported condition oflegs 20 and 22, a great majority of the bending stress in the body 12 isconcentrated in the bridge 18. The stress in bridge 18 causes it to bowoutwardly until it makes contact with an inside surface 40 of a tubularin which the seal 10 is being set. Once contact is made at surface 40, aload useful for creating the desired seal begins to build. As gaugerings 24 and 26 continue to be urged into closer proximity with oneanother it will become apparent that radiuses 32 and 34 are alsoimportant to reducing stress in the seal body 12. In the position ofFIG. 2, it will be easily appreciated that were the radiuses to besignificantly sharper, much higher stress would be experienced by theseal body 12 at the contact point with such radiuses. It has beendetermined by the inventors hereof that a radius range of from about0.13 inches to about 0.16 inches produces a desirably low stress in theseal body 12.

It is to be appreciated from FIG. 2 that the bridge 18 is deformed suchthat over an axial length thereof, more than 180 degrees ofrepositionment is represented. In other words, the bridge 18 is deformedfrom relatively flat to beyond U-shaped. In the illustrated embodimentof FIG. 2, it will be appreciated that the bridge is nearly a closedteardrop shape 44. In the condition illustrated in FIG. 2 substantialsealing force is applied to surface 40 such the pressure may be held ineither direction relative to seal 10. Important to notice as well isthat because of the teardrop shape of bridge 18, backlash in the settingsystem is better absorbed than in prior art sealing systems. This isbecause with a reduction in the sealing force at gauge rings 24 and 26move slightly away from each other. When this occurs elastic resiliencein the bridge 18 will tend to straighten the two sides 46 and 48 of theteardrop shape 44. This will tend to increase loading at interface 50with surface 40 rather than to reduce loading at interface 50 whichwould have been common in the prior art.

Referring now to FIGS. 3 a through 3 f retrieval of seal 10 isillustrated in sequence. It is important to note in this sequence ofdrawings the relative positions of the legs 20 and 22 versus theteardrop shape 44 as they are illustrated in FIGS. 3 b and 3 c. Uponreview of these figures it will become apparent to one of ordinary skillin the art that the teardrop shape 44 is maintained substantially intactwhile the legs 20 and 22 and the roots 36 and 38 are subjected totensile bending stress and experienced a greater degree of movement.This is beneficial since as noted above the legs and roots are protectedfrom bending stress during initial setting of this seal. Therefore theyhave significantly greater elasticity than the bridge 18, which has beenwork hardened, at this stage in use of the seal 10. With reference toFIG. 3 d, it can be ascertained that the bridge 18 has begun to reopenbut it is also important to note that the interface 50 has come out ofcontact with surface 40 by a significant margin at this point in theretrieval process. While more bending stress is being added to bridge 18at this point in the process a rupture is less likely to create aproblem. Moving on to FIGS. 3 e and 3 f the seal has already beensubstantially withdrawn and again rupture at this point is lessdamaging. It will also be appreciated by the reader at legs 20 and 22and roots 36 and 38 are now significantly deformed but because thisdeformation is the first bending stress experienced by those components,they are highly likely to survive that stress.

The foregoing description might be reasonably understood to relate toonly a symmetrically positioned seal. It is to be appreciated howeverthat depending upon the type of movement utilized during the settingprocess it is sometimes advantageous to prepare the seal 10 as anon-symmetrical device. More specifically, and utilizing one-gauge-ringmovement as an example, if gauge ring 24 is moved toward gauge ring 26while gauge ring 26 is held in a stationary position it is reasonablylikely that the teardrop shape 44 will contact the inside surface 40 (atinterface 50) before the seal 10 is fully set. While it is subtle in thedrawings utilized to exemplify the invention, careful consideration ofthe illustrated position of interface 50 relative to a centerline of theseal 10 will show that it is offset in the direction of gauge ring 24.This is because of the contact with surface 40 prior to fully setting ofthe seal 10. Once contact is made at interface 50, the positioning ofside 48 is relatively fixed and the positioning of side 46 will continueto change. Side 46 will deflect under the impetus of gauge ring 24 tohave a greater curvature than that of side 48. Because it is desirableto promote symmetry as much as practicable in teardrop 44 it may bedesirable in certain applications to vary a thickness of the seal body12 over its length. More specifically is possible to utilize thicknessof seal body 12 to encourage early deformation in some portions of theseal body 12 and delayed deformation in other portions of the seal body12. Generally speaking in order to enhance symmetry in the teardrop 44 alesser thickness at the more relatively fixed end of seal body 12 willallow side 48 to more readily deform into a desirable position.Likewise, while the angles of the angled surfaces 28 and 30 and theradiuses 32 and 34 need not be symmetrical and in some applications maybe better operable by being disparate. It is further to be understoodthat although the disclosure hereinabove describes an embodiment whereeach component is mirrored on both axial ends of the seal 10, albeit notnecessarily with the identical dimensions or shapes, the teardrop shapecan still be created with asset of the identified components on but oneaxial side of the seal 10 with the other side being simply attached to acarrier component.

While preferred embodiments have been shown and described, modificationsand substitutions may be made thereto without departing from the spiritand scope of the invention. Accordingly, it is to be understood that thepresent invention has been described by way of illustrations and notlimitation.

1. A seal comprising: a seal body having: a bridge; a leg extending fromthe bridge; and a gauge ring in operable communication with the leg, thegauge ring including a support surface for the leg, the gauge ringinteracting with the seal body to cause axial compression thereof,thereby forming a teardrop configuration of the bridge.
 2. A seal asclaimed in claim 1 wherein the seal body is formed such that residualstress therein is minimized.
 3. A seal as claimed in claim 1 wherein asecond leg extends from the bridge at an axially opposite end of thebridge.
 4. A seal as claimed in claim 3 wherein the legs are of distinctdimensions from one another.
 5. A seal as claimed in claim 4 whereindistinct dimensions are at least one of length, thickness and angle. 6.A seal as claimed in claim 1 wherein the support surface for the leg isat an angle relative to an orthogonal plane through the seal that isgreater than about 45 degrees.
 7. A seal as claimed in claim 1 whereinthe support surface for the leg is at an angle relative to an orthogonalplane through the seal that is less than about 90 degrees.
 8. A seal asclaimed in claim 1 wherein the support surface for the leg is at anangle relative to an orthogonal plane through the seal that is about 60degrees.
 9. A seal as claimed in claim 3 wherein the seal furthercomprises a second gauge ring having a support surface for the secondleg.
 10. A seal as claimed in claim 9 wherein the support surface of thegauge ring and the second gauge ring are one of angled identically toeach other or angled independently of each other.
 11. A seal as claimedin claim 1 wherein the gauge ring further comprises a radius extendingfrom the support surface.
 12. A seal as claimed in claim 1 wherein theradius is greater than about 0.13 inches.
 13. A seal as claimed in claim1 wherein the radius is less than about 0.16 inches.
 14. A seal asclaimed in claim 11 wherein the further includes a second gauge ringhaving a second radius.
 15. A seal as claimed in claim 14 wherein theradiuses are different from one another.
 16. A seal as claimed in claim1 wherein the support surface substantially prevents bending stress inthe leg during setting of the seal.
 17. A method for setting a seal in atarget tubular comprising: axially compressing the seal claimed in claim1; bending the bridge into a teardrop shape in sealing contact with thetubular; and substantially preventing introduction of bending stressinto the leg.
 18. The method as claimed in claim 17 further comprisingretrieving the seal by: introducing a tensile force to the leg;subjecting the leg to bending stress; and substantially delaying theintroduction of tensile bending stress in the bridge.
 19. The method asclaimed in claim 17 further comprising substantially returning the sealto a retrievable condition prior to introducing substantial tensilebending stress into the teardrop shape.
 20. A seal comprising: a sealbody configured to form a teardrop shaped seal member upon axialcompression of the seal body; and a gauge ring in operable communicationwith the seal body and capable of applying an axial load on the sealbody.
 21. A downhole sealed system, comprising: at least one tubularmember of the tubular system disposed in one of radially inwardly of orradially outwardly of another component of the system; and a sealdisposed annularly at the tubular member, the seal having a teardropshaped cross section.